Mechanical grinding methods for preparing polymers in particulate form are useful only with polymers that possess sufficient modulus or brittleness to be broken down into particulate forms. For certain polymers such as polyacrylates, polyethylene, polypropylene, or ionic copolymers, comminution is difficult and must be carried out under cryogenic conditions. The process of this invention provides a process for producing comminuted polymer structures without cryogenic "grinding".
The process of this invention is an improvement over the processes taught in U.S. Pat. Nos. 3,752,784 and 3,753,932. This patent application is related to "A Process For Preparing Particulate Microporous, Open-Celled Polymer Structures", coassigned, and filed concurrently herewith in the name of Francis Edward Jenkins, bearing U.S. Ser. No. 576,634. It is also related to "A Process For Preparing Microporous, Open-Celled Cellular Polyblend Structures", coassigned, and filed concurrently herewith in the name of Francis Edward Jenkins, bearing U.S. Ser. No. 576,631.